Multiwall bags are useful for packaging many different types of products, such as pet food, flour, sugar, fertilizer, sand, dry cement, yard waste, and the like. Typically, the bags are constructed with several layers of substrates: typically at least one kraft paper with at least one plastic film, foil or laminated sheet. The substrates are laminated (attached) together with adhesives. Depending on the content and weight of the product, the adhesive is applied to the entire substrate or in a specific patterns or lines.
The laminated substrates are cut to appropriate size and then filled by machinery, and the ends are formed. During the filling process, it is desirable for the substrates to remain adhered. Delamination of the substrates during the filling stage causes inadequate and inefficient filling, resulting in process delays and waste.
In recent years, there has been a growing demand for finding ecologically friendly resources to reduce the impact on human health and the environment. Adhesives made from natural components, such as starch is renewable and thus, environmentally conscious. Starch-based adhesives are widely used on celluosic board for attachments; however, they are not generally used for flexible plastic substrates due to no or low adhesion properties. Traditionally, synthetic adhesives, particularly, acrylic polymer based pressure sensitive adhesives, have been used for flexible plastic substrates.
There is a need in the art for a laminating adhesive that adheres to both cellulosic board and flexible plastic films that can be prepared at low cost and with low ecological impact. The current invention fulfills this need.